82 CHEMICAL PROPERTIES OF SOIL 



condition capable of being worked. If the clay has undergone 

 deflocculation or resolution into its finest particles it becomes 

 sticky, persistently wet, and "puddles" when worked. The 

 desirable flocculation or granulation of the clay particles is aided 

 by certain salts and acids, and hindered, sometimes for an indefinite 

 period, by alkalies. 



61. Effect of Acids, Alkalies, Salts, etc. 



A few grams of clay are rubbed up with distilled 

 water in a mortar, the thin paste diluted to i litre, 

 allowed to stand for a short time, and the turbid liquid 

 poured into a number of cylinders (lOO c.c. measuring 

 cylinders or Nessler tubes do excellently) ; one of these 

 cylinders is used as a control, and to the others are 

 added the following materials : — 



N 

 {a) I c.c. — Hydrochloric acid. 



N 

 (^) 0*5 c.c. — Hydrochloric acid. 



(^) I c.c. I per cent. Sodium chloride solution. 



id) I c.c. I per cent. Calcium chloride solution. 



(^) 4*5 c.c. Lime water. 



N 

 (/) 0*5 c.c. — Sodium hydroxide. 



(^g) I c.c. I per cent. Sodium phosphate solution. 



The respective times taken for the columns of liquid 

 to become clear, i.e. for the clay to flocculate, should 

 be noticed, and the materials classified according to 

 their activity. By varying the quantities of salts used, 

 the relationship between the amount of salt present 

 and the extent of flocculation may be determined. 



The flocculating effect of lime in a soil is due to its 

 conversion into carbonate and then into bicarbonate. 

 Solutions of the latter salt have a very aggregating 

 effect. 



